python: use set(A) - set(B) to find items that are in A but not in B

gistfile1.txt

#!/usr/bin/env python

# Given a list of ingredients needed for a recipe, represented as strings, and a list of ingredients you have in your pantry,
# write a function to return the minimum number of additional ingredients you need to buy to make the recipe.
# If you want to do some extra credit, add expiration dates to the pantry items, and only account for food that isn't expired.

# Example:

# Input:
# recipe = ["eggs", "flour", "sugar", "butter"]
# pantry = ["sugar", "butter", "milk"]

# Output:
# 2
# (you can submit your answers by replying to this email with a link to your solution, or share on LinkedIn, Twitter, Mastodon, or Bluesky)


def find_missing_ingredients(recipe, pantry):
    # set(A) - set(B): Elements that are in A but not in B.
    return len(set(recipe) - set(pantry))

if __name__ == "__main__":
    cases = [
        {
            'recipe' : ["eggs", "flour", "sugar", "butter"],
            'pantry' : ["sugar", "butter", "milk"],
            'missing' : 2
        },
        {
            'recipe' : ["water"],
            'pantry' : [],
            'missing' : 1
        },
        {
            'recipe' : ["flour", "yeast", "salt"],
            'pantry' : ["flour", "salt"],
            'missing' : 1
        },
        {
            'recipe' : ["eggs", "flour", "sugar", "butter", "milk"],
            'pantry' : ["eggs", "flour", "sugar", "butter", "milk"],
            'missing' : 0  # All ingredients present
        },
        {
            'recipe' : ["tomato", "onion", "garlic", "basil"],
            'pantry' : ["basil"],
            'missing' : 3
        },
        {
            'recipe' : [],
            'pantry' : ["sugar", "butter"],
            'missing' : 0  # No ingredients required for the recipe
        },
        {
            'recipe' : ["cheese", "bread"],
            'pantry' : ["cheese", "bread", "milk", "butter"],
            'missing' : 0  # Extra pantry items, but no missing ingredients
        },
        {
            'recipe' : ["salt", "pepper", "olive oil"],
            'pantry' : ["salt", "pepper", "olive oil", "vinegar"],
            'missing' : 0  # All ingredients are present, including extra pantry items
        },
        {
            'recipe' : ["flour", "eggs", "sugar"],
            'pantry' : ["sugar", "flour"],
            'missing' : 1  # Missing eggs
        },
        {
            'recipe' : ["chicken", "rice", "broth", "carrots"],
            'pantry' : ["rice", "carrots"],
            'missing' : 2  # Missing chicken and broth
        },
    ]

    for i, case in enumerate(cases):
        recipe = case['recipe']
        pantry = case['pantry']
        expected_missing = case['missing']
        actual_missing = find_missing_ingredients(recipe, pantry)

        try:
            assert actual_missing == expected_missing, \
                f"Test case {i+1} failed: expected {expected_missing} missing ingredients but got {actual_missing}. Recipe: {recipe}, Pantry: {pantry}"
        except AssertionError as e:
            print(e)
        else:
            print(f"Test case {i+1} passed.")